Classification



Nov. 17, 1942. i

A. W. FAHRENWALD CLASSIFICATION Filed March e', 1940 4 sheets-sheet 1imnwwIll ATTORNEY.

NV 17 1942. A. w. FAHRENWALD 2,301,937

CLASSIFICATION Filed March 6, 1940 4 Sheets-Sheet 2 ATTORNEY.

Nov. 17, 1942. A. w. FAHRENWALU .2,301,937

CLASSIFICATION Filed March 6, 1940 4 Sheets-Sheet 3 A TTORNEY,

4 Sheefs-Sheet 4 Milli Nov. 17; 1942. AA. w. FAHRENWALD CLASSIFICATIONFiled March 6, 1940 iatented Nov. 17, 1942 UNITED STATES PATENT OFFICECLASSIFICATION Arthur William Fahrenwald, Moscow, Idaho, as-

signor to The Dorr Company, Inc., New York, N. Y., a-corporation ofDelaware Application March 6, 1940, Serial No. 322,455

9 Claims.

The invention relates tol process of and apparatus for the hydraulicseparating, classifying or fractionating of pulp bearing different typesof solids of uniform or even different sizes, or bearing solids of thesame type but of different sizes, or bearing mixtures of the foregoing;such a pulp is exemplified by what is known as metallurgical pulp orthat which may be known as pulp because of the solids includingmiscellaneous mixtures such as earth bearing materials including gravel,clay, or the like, wherein there are included relatively large orquickly settleable solids frequently referred to as sands or concentrateand light or fine particles of a character less readily settleable-orwhich are setwhich liquid with fine particles therein passes i asslimes.

Provision is made for an outflow or hydraulic passing of the larger ormore readily settleable type of solids from the bottom of the body asand when an unbalanced condition is created'or becomes establishedsufficient to cause such outflow because of a building up of solids andincrease of density within the body sufficient to overcome a relativelyconstant back pressure which -is provided and maintained for preventingan outflow of solids except when such unbalanced conditions exist at theoutflow region leading from the lower portion of the body. In

' this connection it'will be noted that in the pertleable only withdifficulty or even after special v preparatory treatment-and which passoff as suspended solids in the outilowing liquid in'a form ofliquid-solids mixture which is commonly referred to as slimes.

The process or apparatus is also applicable to the treatment ofmetallurgical pulps bearing relatively heavy metallic particles such asgold and which particles although small, are more readily settleablethan the sand in which they are found or exist.

An object of the invention is to provide a process of and for thefractionating of pulps or mixtures of readily settleable solids andsolids which are not readily settleable whereby for the performing ofthe process there may be employed apparatus which is relatively small insize and efficient and effective in operation as compared with thepresent-day apparatus.

I have developed a novel process and apparatus of a continuous mode ortype' which for the performance and operation thereof is based upon thefact that a liquid-solids bodyof pulp may be established in aclassifying zone or area and be maintained therein in a condition inwhich the settled solids and that section of the liquid in which theyare primarily found constitute a mobile -Inass which is attainable andrealizable by the proper actuated movements imparted to an underlying'constriction member having numerous discharge openings or orificeportions from which Water is forcibly discharged upwardly into theoverlying liquid solids body in quantities sufficient for realizing thedesired forming of the process and in operating the apparatus there isemployed means for insuring a constant back pressure which can be reliedupon for balancing the hydrostatic pressure or static head at the bottomor lower portion of the liquidsolids body except when incident to andfollowing the feeding of pulp lto the body there isA realized theincrease in the density and solids loading of the body with a consequentpressure head at the lower portions of the body suicient to overcomesaid back pressure. I

'Ihe various objects and aspects to which the invention is directedprimarily revolve about the features broadly referred to above.

Further objects, aspects and features of the ao invention wm be morevividly brought out by' the more detailed description which follows andthey are more sharply dened or distinguished in and by the claimshereof.

In the following description and in the claims, parts will be identifiedby specific names for convenience, but they are intended to be asgeneric in their application to similar parts as the art will permit. Inthe accompanying drawings there has been illustrated the best embodimentknown to me, but such embodiment is to be regarded as typical only ofmany possible embodiments, and the invention is not to be limitedthereto.

Reference is now made to said accompanying drawings which form a part ofthis specification.

In said drawings- Fig. 1 is a plan view of one form of apparatus forrealizing the invention hereof; in this figure certain parts are shownbroken away whereby certain other parts appear either in horizontalsection or in plan;

Fig. 2 is a vertical sectional View of the apparatus taken as on theplanes indicated by the broken line 2-2 of Fig. 1 looking in thedirecconstant level because of an overflow weir over tion of the arrows;this Fig. 2 for convenience is referred to as a vertical longitudinalsectional view;

Fig, 3 is a transverse. vertical sectional view taken as on the planeindicated by the line 3 3 of Fig. 1 looking in the direction of thearrows; Fig. 4 is a view diagrammatically illustrative n of features ofcertain operating parts of another General A main frame i is provided asthe main support for the classier 2l.or classifying element proper.,Upon this frame there is mounted suitable motivated mechanism forimparting reciproi catory movement to said classifier or to at leastsome member thereof.

In each form of classifier illustrated there is a funnel-shaped member23 underlying an apertured flow constriction member or plate as 2t (seeFig. 3) and a cylindrical wall 32. Within the funnel-shaped member 23and below the constriction member 2t there is provided a space 25sometimes referred to as a hutch compartment or zone within which waterunder pressure'is received initially. Within the cylindrical Wall 32 andimmediately overlying the flow constriction plate there is provided aclassifying space or zone 42 wherein a liquid-solids body undergoingclassication is maintained at an operative level normally determined byan overflow Weir E3@ (Fig. 3) which is sometimes identified as a high orslimes weir. Water supplied under pressure to the hutch compartment 25,is forcibly passed upwardly through relatively uniformly spaced oriiices38 in that area of the constriction member 26S that comprises the lowerlimits or boundary of the liquid-solids body or the classification zone42 that holds that body. The water is delivered upwardly into the lowerportion of the liquidsolids body immediately overlying the oricesecasomar Main frame The main frame includes longitudinally-extendingbeams or longitudinal channel members 2, transversely-extending headersor transverse channel members 3 and motor supporting platform li. Theframe also includes necessary tie plates as 5 and diagonal bracingelements or,`

members as t all of which are suitably connected as by bolting, rivetingor welding so as to form a relatively self-contained, rigid and strongsupporting structure or base member.

Motivated actuating mechanism A motor i is securely mounted upon theplatform i and it provides a' driving pulley 8 which in turn transmitsthrough the medium of a belt 9 power to a driven pulley it secured to ahorizontally-extending crank shaft il. Illhis crank shaft il is mountedin horizontal bearings or pillow blocks i2 suitably secured to orsupported on the main frame.' The crank i3 of the crank shaft ii hasconnected thereto 'so as to be actuated therefrom end M of a connectingrod i5. The other end i 6 of the connecting rod is referred to as theclassifier end and is suitably connected at and to the outer end portionil of an arm 22 extending from some part of the classi- :der or to somemember of the classifying construction carrying or having drivingconnection with the flow constriction member. k

In the construction shown, the classifier end i@ of the connecting rodi5 has operative 'engagement with the outer end il of the arm. 22extending from the funnel-shaped member 23 Whichin turn carries the flowconstriction plate 2 as is clear from an inspection of Fig. 3. It willhereinafter be made apparent that this arm 22, and the member by whichit is carried or from which it extends, has imparted thereto back andforthr oscillatory movements in horizontal directions about avertically-extending axis, or as otherwise expressed, repetitiveoscillatory movement of relatively limited arcuate range in a horizontalpath. This repetitive movement is provided essentially for imparting therequired movement l to the constriction plate 24; (a) whereby theupowing water has more uniform dispersion within tion revolves about amovement of the ow conylower portion of the liquid-solids body.

A motivated mechanism is therefore provided for imparting the requisiterepetitive movement to the flow constriction member which movementaccording to the form of apparatus illustrated `is a back and forthhorizontal oscillatory movement. within a relatively small arc about averticallyextending axis that is concentric with the hollow cylinder orcircular wall 32 that marginally defines the outermost limits orboundary of the liquid-solids body.

. parent how and Why the motor actuated mecha'- l and throughout theliquid-solids body; and (b) whereby the longitudinal engagement betweenAthe upper surface of the plate and any'solids touching it will furtherthe maintaining of the desired mobile characteristics of theliquid-solids mass. Any suitable construction may be used foroperatively associating the end I6 of the connecting rod with the outerend l1 of the arm 22. In the construction shown the outerend of the arm22 is provided with oppositely disposed curved surfaces I8 and anopening o for the reception of the end i6 of the connecting rod l5.

`It will be noted that the connecting rod end I B,

is screw threaded and that upon this section there are locatedpositionable washers or inter- Y mediate blocks I9 in the form ofbearing members disposed for engaging the curved surfaces I8. 'I'hesewashers are normally held in place in. adjusted position by nuts 20.

From what has preceded, particularly in connection with the drawings, itwill be readily apnism functions to impart repetitive movement of thedesired character to the flow ,constriction plate.-

Classifier or classifying element proper of Figs. 1 to 3 On the mainframe there is located a bearing 26 which may be referred to as aclassifier main bearing, which is secured in place on the main frame inlany suitable manner as through the medium` of bolts. From one point ofview this bearing 26 may be considered as a part of the main frame, oras part of the stationary supporting structure, and provides astationary or fixed supporting main bearing for a movable bearing member21.

A movable bearing member 21 is mounted in the stationary bearing 26 in amanner whereby the movable member 21 and the parts supported therefromand movable therewith, can have repetitive horizontal turning movementimparted thereto through the medium of the actuating mechanismheretofore referred to. In order to provide for ease of movement, ananti-friction type of bearing construction 28 or anti-friction elementhas been interposed between the stationary and moving bearingmembers 26and 21 respectively.

The upper end of the movable bearing member 21 is provided with a flange29 and receives the lower end 30 ofthe funnel-shaped member 23 thatprovides therein the section of the classifier which is frequentlyreferred to as a hutch compartment and which' as previously indicated isimmediately below the apertured flow constriction plate 24. Thefunnel-shaped member 23, as the name implies, is in the form of atruncated base portion of an inverted cone and the lower or small end 3Uthereof is rigidly connected in any suitablemanner to the flange 29, infact, a strong and water-tight joint is provided between them.

The upper or large end of the funnel-shaped member 23 is provided with aflange 3|. The lower end of the hollow cylinder 32 is provided with theflange 39. The hollow cylinder or cylindrical member 32 provides acircular marginal wall. The cylindrical member 32 and the apertured ilowconstriction plate 24 are'located upon the funnel-shaped member 23 andare connected thereto as through the medium of bolts 33 which passthrough the flanges 3| and 39 and the interpositioned margin of the flowconstriction plate 24. In order to prevent leakage through or past thebolted joint construction just referred to, suitable packing material orgaskets are provided at 35. Th'e'upper end of the circular marginal wall32 is horizontal and provides at 34 that which may be referred to as ahigh slimes overflow Weir that determines the normal operative level ofa liquid-solids body which is defined as to its outer marginal limits bythe circular or cylindrical wall 32 and as to its lowermost limits bythe flow constriction plate 24. During the'normal operation of theclassiiler liquid with the less readily settleable or ner solidssuspended therein passes over this high Weir as overflow. Suchoverflowing liquid with the ner solids suspended therein is usuallyreferred to as slimes. The slimes overflowing said Weir 34 enter theperipheral launder 36 and pass therefrom through a discharge section 31leading from the classifier.

As to the flow constriction member 24 this is shown as ahorizontally-extending ilat plate and comprises an apertured portion orapertured general section in which there are relatively small liquidupflow openings 38 that are disposed in a relatively uniform orsystematic manner throughout the area or regions thereof immediatelyunderlying the liquid-solids body undergoing solids fractionating orclassifying treatment in the classifying zone of the classifier, to wit,in the annular space or zone 42.

The classifier is constructed so as to provide for the automaticdischarge of the more readily settleable solids during the period ofnormal operation of the classifier consequentto a feed of pulp theretoto be treated and to that end there is embodied in the classifierconstruction means providing a solids discharge area or passagewayleading from the lower portion of the liquid-solids bodyin theclassifier, to wit, from the 'lower interior portion of the-classifyingzone 42 to a region in which the solids conveyed therethrough aredistant from the classifying zone or space 42. To provide such means theclassifier of Figs. 1 to 3 is constructed so as to include a baillemember below or through which there is provided a solids dischargepassageway or area and also so as to include means providing a dam orlow overflow weir construction. In the embodiment of said Figs. 1 to\3the baille member is cylindrical in horizontal cross section and isprovided by an inwardly disposed cylindrical member 40 which extendsdownwardly from an elevation somewhat higher than that of the normalsurface level of the liquid to a locality close to but vertically-spacedabove the apertured flow constriction member 24 whereby the solidsdischarge area or passageway is provided for or left at 4| forthepassage thereinto and therethrough of certain quantities of theconcentrates or larger or more readily settleable type of solids foundwithin the lower portion of the liquidsolids body in zone 42. In theconstruction shown in said Figs. 1 to 3 inclusive this baille member 40extends all the way down to the flow constriction plate 24 except forthe discharge area or open sections left at 4|. As part of the solidsdischarge means there is also included an innermost cylindrical member43. This is connected to the flow constriction plate 24 as by means of4the bolts 44 and extends upwardly therefrom.

This member 43 is constructed to provide openings' or passage area at 45through which solids can pass incident to their overflowingverticallyadjustable weirs 16. The weirs 16 are herein referred to asthe low solids overflow weirs and it will be noted that they aredisposed at elevations lower than that of the higher or slimes overflowweirs 34. The weirs 16 are provided by and at the upper edges of curvedplates 11 that substantially llt the juxtapositioned contour of thecylindrical member 43 These curved plates have vertical edges that aredisposed so as to have sliding engagement in vertical guide-waysprovided at 18. These plates 11 may be vertically positioned to attainany desired operative elevation for the overflow `weirs 16 `thereofthrough the medium of screw-threaded vertically-extending rods 19 andthe cooperating hand-wheels or nuts which have bearing portions 8| thatderive support from the horizontal feed distributing plate 52 and whichare turnably held thereupon by the retaining rings 82.' In theconstruction shown the cylindrical baille member 40 is directly securedto the cylindrical low weir providing member 43 in any suitable manneras by means of brackets or connecting braces 46.` The result of theconstruction described is that the outermost or cylindrical marginalwall 32, the cylindrical baille member 40 and the inner cylindrical lowweir providing member A3 all have the same angular oscillating movementimparted thereto as that which is imparted to the funnel-shaped member23, and thereby to the flow constriction plate 2Q.

The central section til of the dow constriction plate 2d is solid orimperforated except for the central discharge opening du provided forthe asomar fractionating or classifyingzone l2 of the classifier. Y

In the instance of certain pulps very ilne solids of heavy specific'gravity pass downwardly through the orifice portions of the constrictionplate into the underlying space or hutch compartment. This particularlyhas reference to partidown passage of the heavier larger solids, to wit,

at 56' to the imperforated central section lll whereby there is avoidedthe leakage of pressure water from the hutch compartment into the sandsreceiving space 4B. The pipe or conduit 55 passes downwardly through themovable main bearing 2li and is provided whereby sands can freely passfrom the sands receiving space il@ to .a regionoutside of or remote fromthe classifier.

Suitable provision is made, to wit, such as is accomplished by packingmaterial -as at 5l for preventing the outflow or escape of pressurewater frombetween theexterior of the conduit55 and the movable bearing2l through which it extends.

Xt has been pointed out that the liquid-solids body undergoing treatmentis defined as to its outermost marginal limits by the cylindricalmarginal wall 32. As' to its innermost limits it is defined by thecylindrical bale member d6. The members or parts 32, 24 and do justreferred to delineate'or outline the space or zone which has beendesignated vas 42 and which has herein been referred to as theclassifying zone. In this zone there is maintained a liquid-solids bodyof constant volume but in which the specific gravity or effectivehydrostatic pressure head at the bottom is changeable as according tochanging rates of feed, differences in types of pulp supplied, or evenother operating conditions which may be experienced as the processcontinues.

A feeding means for the pulp to be treated comprehends a small hopper 50which is supported through the medium of horizontally-spaced legs 5lextending upwardly from a horizontal feed or pulp distributing plate 52that is secured to the upper end of the cylindrical baille member 40 asbymeans of angle irons or brackets provided at 53. The outer edgeportion 54 of this distributing member 52 is preferably at or proximatethe normal surface level of the. liquid-solids body in the classierwhereby the pulp dropping or plunging therefrom for classifyingtreatment is discharged into the liquid-solids body without creating1mdue disturbance therein.

Reference=has heretofore been made to the fact that the chamber 25 belowthe construction plate -24 and within the funnel-shaped member 23 may bereferred to as a hutch compartment. Thisl lsame compartment 25-may bereferred to as a pressure chamber `wherein water is received thatbearing member 5l, which is normally mounted cles of relatively heavymaterial such as gold. These hutch products are obtainable from saidcompartment because of a passageway 5d leading downwardly through themovable bearing member 2l and may be collected therefrom through themedium of a flexible connector provided at 56.

Classijer of Fig. 4

The form of apparatus typically illustrated by Fig. 4: follows theprinciple of construction already described in connection with the formof apparatus illustrated by Figs. l to 3 inclusive but certaindifferences as to 'specific features thereof will be apparent from thatwhich follows:

` According to the form of Fig. 4 there is employed the funnel-shapedhutch member 23 that is mounted on the flange portion Z9 of a movable ona stationary main bearing as 26 of Figs. l to 3 and in the same mannerthat the corresponding movable main bearing 2l of Figs. l to 3 ismounted. This hutch member also carries an apertured flow constrictionplate 62 and an outermost cylindrical wall 53 above the plate, all ofwhich are suitably secured together as by bolts after theY manner'of thesimilarly shaped parts of the apparatus shown in Figs. 1 to 3. Water issupplied under pressure as by the flexible connector 59.to the interiorportion or hutch cornpartment which is within the funnel-shaped member23 and below the flow constriction plate 62. In the instance of the formof Fig. 4e the cylindrical member 63 which extends upwardly from theperforated plates has associated therewith a vertically-adjustablecylindrical member b3 that is constructed so as to provide avertically-positionable overflow Weir 6d. This Weir 6d is sometimesreferred to as a low solids overflow Weir and is at an elevation lowerthan that of the higher or slimes overflow Weir 66. The cylindricalmember 83 has vertically-extending slotsA or openings 84 for receivingbolts 85 thereby providing a construction arrangement by which verticaladjustment for the low slimes overflow weir 54 can be realized. Theexterior of the positionable cylindrical member 83 is such as tosubstantially t the interior of the outermost cylindrical Wall 63 andwhen secured in place by the bolts 85 'in effect becomes an extension orpart of the marginal wall of which lthe outer cylindrical extends to anelevation higher than that of the outer cylindrical member 63 and isprovided at and along the upper margin thereof with an overow weir 66which is sometimes herein referred to as a high slimes overflow Weir.From the drawings it will be noted that the slimes overilow Weir 66 isat an elevation higher than that of the solids overflow Weir 64. Thecylindrical member parts thereof all the way down to said perforatedplate. However, there are provided or left in or below the lowermostportion thereof solids discharge area or passageways 61 leading from thelower portions of the interior section providing the classification zone68 to the exterior of the classifying space, or what is the same thing,to a region 'I5 that is exteriorly located with respect to theliquid-solids body that is maintained in the classifying zone 68. Thecylindrical wall 65 marginally defines the outermost limits ofclassifying space wherein the liquid-solids body is located whileundergoing the fractionating treatment.

The apertured flow constriction plate 62 has connected thereto a smallinnermost cylindrical construction or column 69 concentric with themarginal cylindrical Wall 65 just referred to. This smaller cylindricalmember or column constitutes a support at the upper portion of whichthere is carried a feed distributing plate which in turn `supports afeed hopper construction 1I similar to that employed in connection withthe form `of apparatus shown in Figs. 1 to 3. In the instance of theconstruction of Fig. 4 the movable bearing member 6| is provided withonly one opening extending downwardly therethrough, namely, opening 'I2for the delivery therethrough of the hutch products and from which thereextends a flexible hutch delivery pipe or conduit 14 that is connectedby coupling 13 to the lower end of the movable bearing member 6|.

Operation of the apparatus The expression pulp as employed hereinimplies any liquid containing suspended solidsofv l different sizes ofwhich the larger sizes are more that which is known as metallurgicalpulp. It`

may include that which -is a suspension of sand and fine clay. It may bea metallurgical type of pulp yof which there are fine solids not readilysettleable, of which there are coarse solids that are readily settleableand of which there are other solids in very iine sub-division or ofsmall particle size which are more readily settleable than the largesolids because of their much greater specific gravity as compared withthat of the larger but less readily settleable solids. An instance ofthis is realized by the small gold particles in metallurgical goldbearing pulp.

partment is marginally defined by a cylindrical wall of the classifierthat has associated with it a perforated flow constriction plate thatdefines the lowermost limits of the liquid-solids body.

The cylindrical baille member 40 of Figs. 1 to 3 or the cylindricalcentral column 69 of Fig. 4 constitutes inwardly disposed memberscircular in cross section that in effect define the innermost limits ofvtheclassifying zone and of the liquid-solids body within saidclassifying zone. Thus in each form, the'classifying zone or area forthe maintained liquid-solids body is comprised within the space betweenthe concentric marginal body-defining wall on the one hand and thecylindrical structure defining the innermost limits of the liquid-solidsbody on the other hand. This classifying zone and its liquid-solids bodyis defined as to its lowermost limits-by the flow constriction platewhose apertures or discharge orifices aredirectly below theliquid-solids body. l

Assuming that a liquid-solids body or suspension has been establishedwithin the classifying compartment and that the flow constriction plateis being reciprocated or oscillated so as to maintain the mobilesuspension characteristics for the solids within the liquid-solids body,then during thev normal operation of the machine, there is provided acontinual supply of water under pressure into the hutch compartment sothat it can flow upwardly through the orifices of the constriction plateand enter in the form of `iets the lowermost portions of theliquid-solids body. The mechanism for imparting horizontal oscillatingmovement to the flow constriction plate continues in operation. Therepetitive back and forth movements of the horizontal constriction platecause a tangential type of engagement between it and the heavier orsettled solids in the liquid-solids body as they drop or settle intocontact therewith, with the result that there is Ia Aslight oscillatorymovement imparted to` these The material to be treated may be inrelatively dry form but when acted upon for classification, it must bein the form of liquid-solids mixtures or suspensions. volving theseparation of suspended solids by a hydraulic classifying operation intotheA more readilysettleable and the less readily settleable groups withthe line of demarcation between the groups being controllable at will.In starting the operation, there isnrst established a liquidsolids bodyor suspension within a liquid-holding or classifying zone of theclassier. This com- The process hereof is one insolids, of decreasingintensity with increasing distance from the plate so as to cause arelative movement of adjoining planes and a mutual rolling effect allresulting in imparting to the solids `individual as well as groupmobility. This mobile state or condition will continue to be maintainedeven though the supply of water under pressure should be temporarily cutoff and even though there is no pulp feed being introduced into theclassifier. Assuming, however, that water is being supplied underpressure to the hutch chamber so that it flows upwardly through theorices as jets into the liquid-solids body and assuming that no feed isbeing introduced into the machine at that particular time, thenpractically the sole result will be upflow and outiiow of liquid withonly a relatively small amount of fines therein -to and past the highslimes Weir. There will be no appreciable outflow of solids past the lowWeir because there is a substantial quantity thereof at the deliveryside of tile solids discharge area or openings, as 4| of Figs. 1 to 3and ahead of the low solids overflow weirs provided as by Weir or weirs45 of the same figures. Such collection of the heavier` settleablesolids outside of the classifying zone is sufficient to impart a"relatively constant density to the outside liquid-solids mixturecomprising the same and thereby there results a relatively predeterminedconstant back pressure that continuously functionsto oppose the outflowof solids 'or liquid from the bottom of the body to the regions outsideof the classifying zone,

to wit, through the discharge openings or area Mleading from theclassifying zone.

Now assuming the case where the supply of pulp'is relatively continuous,the pulp is continually fed from the hopper over the distributing platewhere it is suitably discharged into the classifying zone. Under suchconditions there is an accompanied loading of solids into theliquid-solids body with the result that there is an increase in densityof the entire liquid-solids body within the classifying zone and aconsequent increase in hydrostatic head of the material at the bottom orlower portion of the liquid-solids body in said zone. The upow orpressure water through and from theorices of the now constrictionmember. and thence into the liquidsolids body has not been interruptedand the mobile characteristics of the body are continued and maintainedbecause of the oscillatory movement which is continuously yimparted tothe flow constriction member. This results in the continual orever-changing position of the solids in the mobile mass within theliquid-solids body whereby the finer particles of the solids arereleased and passed upwardly and ultimately outwardly as nes suspendedin the liquid overflowing the high slimes weir. At the same time becauseof the increase in density and consequent increased hydrostatic pressurethe pressure at the bottom of thev bed becomes sufficient to overcomethe constant baci; pressure or liquid balance whereby there can and doesfollow an outiiow of the sands, settled' solids, or concentrate as theymaybe called, into and through the solids discharge area or openings asdi of Figs.

-i to 3, or Si of Fig. 4, and whereby some of the solids which haveheretofore passed the discharge openings or area will be elevated to aVposition whereby certain quantities 'can be hydraulically transferredover the vertically-positionable low solids discharge weirs provided asat 155 in Fig. 3, or by the relatively continuousvertically-positionablelow solids discharge weir bfi of Fig. 4. Thesolids which are thus discharged past the low discharge weir i5 of Fig.-3 are received within the space t@ which is immediately over thecentral section lll' of the fiow constriction plate 2d. From the sandsreceiving space il@ the discharged solids, sands or concentrates passdownwardly through sands discharge tube or conduit 55 and ultimatelyfrom the classier. In respect to the process and apparatus hereof thefollowing features will be noted:

The process involves the establishment ofv a liquid-solids body which isperipherally dened preferably by a cylindrical marginal wall, and whichis defined as to its lowermost limits by a constriction plate havingopenings leading upwardly therethrough which are distributed relay `mentof the constriction plate and the everchanging position of the sands isfurther aided by the water upowing into the lower portion of ytheliquid-solidsbody. There is a constant outiiow of slimes, to wit, liquidwith fine or less' readily settleable solids suspended-therein, over ahigh slimes overflow and a relatively simultaneous or consequent outflowof sands or concentrate particularly when the density or hydrostatichead within the body is suiiciently great to force the sands or settledsolids outwardly through discharge area provided therefor against aconstantly maintained back. pressure. The

constant back pressure is sufficiently great tov insure the retention inthe liquid-solids body of the mobile characteristics thereof even whenthere has been a cessation of feed thereto. T-here is a hutchcompartment or receiving space below the apertured constriction plate.There is provided means for removing from the hutch compartment orchamber such products or iine solids as may have been passed downwardlythrough the ow discharge openings or orifices of the constriction -plateincident to the normal functioning of the machine. The constrictionplate has imparted an oscillatory or reciprocatory mo'- tion thereto.The action or movements imparted thereto are relatively light and fastand are not of a character to impart more than a local move ment orhorlzontal'shearing type of action to the lowermost portion of theliquid-solids body as a whole with the result that'the upper portions ofthe liquid-solids body remain at a uniform level in a relativelyquiescent state inso far as the reciprocating movements of theconstriction plate or member are involved. The horizontal reciprocationof the flow constriction member or flow constricting member, as it maybe called, also eects a shearing action on the liquid upfiowingtherefrom; it serves as a ow distribution or iiow distributing memberwhereby the upfiowing liquid is disposed relatively uniformly within andthroughout the solids of the liquidsolids body, all of which aids ineliminating and avoiding pulp banks, dead spots, local boiling or potholes in the liquid-solids body. The

portion of the structure which-defines the inner and outer margins orlimits of the liquid-solids body are 'cylindrical or circular in crosssection and are concentric with respect to each other and with the axisabout which they osclllate. Reliance is made upon the physical phenomenathat even though the circular body-defining l liquid-solids body may bereferred to and described as so lmounted and of a character that theyhold the liquid-solids body in and restrain it against any lateralbodily movement even though the apertured flow constriction member orplate underlying the body has repetitive mOVement imparted thereto.

The upflow of liquid under pressure from the flow distributing' openingsof the constriction plate into the lower portions `of the body of liquidoverlying the constriction plate must be in quantitles and at velocityrates for realizing the classifying `and fractionating operation and itmust be suiclently low to avoid pot holes or boiling in the body. Thearrangement of the flow distributing openings in the constriction plateis preferably practically uniform Athroughout more particularly thatportion of the ow distributing member which is immediately-below theliquidsolids body in the 'classifying zone and the repetitive movementof the owconstriction plate is for the'purpose of effecting an intimatedis- 'incident or consequent to the lfeeding of pulp to and loading ofthe liquid-solids body particularly with the more readily settleabletype of solids. The upfiow of liquid from the perforated plate into theliquid-solids should be at a rate sufficient to place the fines in theupper portion of the bed in hydraulic teeter while there is a hinderedsettling condition in the lower portion of the bed when the solidssettling through the teeter zone assume a crowded but mobile state.

I claim:

l. In vthe classifying of pulp solids containing sands and finer orlighter solids, the method comprising feeding the pulp to the upperportion of a liquid-solids bed, which portion is in hydraulic teeter,marginally deiining said bed against lateral bodily movement, definingthe lowermost limits of said bed by a constriction plate having a levelupper surface and having numerous liquid discharge orifices disposedsubstantially throughout the area thereof that is immediately below themarginally defined bed, providing a solids discharge area leading fromthe lower portion of said bed to regions spaced therefrom, continuallypassing liquid under pressure from the liquid discharge openings of saidconstriction plate upwardly into the bed at uniform relativelynon-pulsating velocity rates sufficiently high for the classifying orfractionating operation but below rates apt to create eddying therein,avoiding imparting repetitive vertical movements 4to said constrictionplate but continually imparting to said constriction plate repetitivehorizontal movements of relatively limited lrange whereby the settledsolids of the bed as well as the teetering solidsthereof constitute amobile mass, overflowing as slimes liquid with certain of the lighter lor flner settleable solids therein marginally from the normal level ofthe liquid, imposing ya relatively yieldable but maintained backpressure constantly acting in opposition to the outward passage of sandsinto, through and from the .solids discharge area and functioning toprevent outward passage of sands except when automatically overcome bythat sufficiency of outwardly directed pressure which followsconsequentto the feeding of pulp during the normal performing of theprocess whereby to avoid any excess accumulation of sands within thebed. l

2. In operative combination in a continuous classifier for fractionatingpulp embodying readily settleable sands and solids that are less readilysettleable, a container for a mixed liquidsolids body including innerand outer bodydeflning annular Walls and a bottom flow distributingmember with flow discharge orifices distributed throughout the areaimmediately' underlying said body which is located so that it surroundsthe inner annular wall and which is marginally limited by the outermarginal wall, means for supplying water under pressure to the undersideof said fiow distributing member for forcible delivery upwardly into andfrom said flow discharge orifices, means for imparting to said flowdistributing member repetitive horizontal movements to further thedistribution of water within the bed and for imparting movementsfavorable to the maintaining of the settled solids in the body in amotile state and at the same time avoiding imparting to the flowdistributing member any repetitive up and down movement whereby to avoidbodily raising or lowering of the mixed liquid-solids body, a highslimes Weir functioning at constant elevation that is the same as thenormal operative level of the body and over which liquid with lightersolids suspended therein continually pass as eflluent from theclassifier. and settled solids outflow means including a sandspassageway and a sands overflow Weir normally functioning at constantelevation lower than that of the slimes Weir whereby sands in saidpassageway offer constantly acting back pressure against which sandsmove and outflow as they accumulate during the normal feeding of pulp tothe body to overcome the continuously acting bacli pressure, the backpressure being suiiicient to insure retention of enough sands in thebody to maintain an individually mobilized mass of settled sands in thebody.

3. In operative combination in a continuous classifier for fractionatingpulps bearing suspended solids in the form of readily settleable sandsand finer solids which are less readily settleable, means providing acircular wall for marginally confining a mixed liquid-solids body andfor retaining said body against lateral bodily movements, ahorizontally-movable constriction plate providing a level upper surfaceof constant elevation disposed below said wall so as to define thelowermost limits of the body and provided with flow-discharge orificesimmediately below the body, means for supporting the flow constrictionplate whereby it can have imparted thereto repetitive horizontaloscillatory movements about a vertically-extending axis concentric withthe circular wall and without having bodily up or down movements forthereby avoiding any bodily raising and lowering of the mixedliquid-solids body incident to such repetitive movements, feeding meansby which incoming pulp is continuously delivered and distributed to theupper portion of the body, means associated with the flow constrictionplate disposed at the underside thereof for providing a pressure chamberadapted to receive hutch products passing thereto downwardly through theapertures of the constriction plate, means for continuously supplyinghydraulic water under pressure into the chamber and therefrom upwardlythrough the orifices of the plate into the overlying liquid body andunder pressure suflicient to maintain /the upper portion of the body inteeter, marginal outiiowmeans having a circular high overflow sectionthat rises to the normal operative surface level of the body whileconcentric with respect to said vertical axis and by which liquid withcertain of the finer solids continually pass as slimes from the body,means for horizontally oscillating the constriction plate relative tothe liquid body for'thereby furthering the distribution of water intoand through saidv body which is normally ever changing and-V forimparting tangential movement` to the settled solids immediately overand which from time to time may engage the upper surface of the flowconstriction plate,solidsdischarge means leading from the lower interiorportion of the body-holdi g section and provided with a bailled circularl w sands overflow Weir of normal constant elevation andA concentricwith said vertical axis for lpermitting the automatic outflow of heaviersolids from the lower portion of the liquid body consequent to increasein the density of the body incident to the continuous feeding of pulp tothe body, and means for passing hutch products from the lower interiorportion of said pressure chamber. k

4. A continuous classifier for metallurgical pulp and the likecomprising in operative combination a container functioning at aconstant elevation for a maintained liquid-solids body having circularconfining walls with a marginal slimes overflow weir at the upperportion thereof normally functioning at constant elevation and a bottomconstriction plate with flow discharge orices distributed lthroughoutthe area immediately below the body within said circular confiningvwalls and also normally functioning at constant elevation, a casingmember providing a hutch compartment therein at the underside of theconstriction plate, supporting bearings by which the container issupported to permit oscillatory movement 'of limited arcuate range inhorizontal paths about a vertically-extending axis but so that novertical movement is imparted to the containers, means for supplyingwater under adjustable pressure to the interior of the hutch compartmentand for thereby forcibly delivering water into the flow discharge oricesand upwardly therefrom at relatively uniform flow rates and in a mannerwhereby pulsated delivery is avoided, means for imparting horizontaloscillatory movements to said container, and settled solids dischargemeans providing an outow passage leading .from the zontal movementsthereto without imparting up or down movements thereto, means forsupplying water for delivery constantly and relatively uniformlyupwardly through the apertured portion of the member into the regionimmediately above the same, a marginal wall extending upwardly to apoint above the apertured member and providing with the latter aclassifying space wherein a 1 liquid-solids body is located and normallymaintained while undergoing treatment for the frac- -tionating of thesolids into different groups of` iines and sands and which marginal wallis disposed so as to hold said body 'against lateral bodilydisplacement, a fines overflow weir of normal constant elevation thatdetermines the normal level of the liquid body which is laterallyconfined by the marginal wall, and meansleading upwardly from the lowerportion of said liquidsolids body and providing a sands overow Weir ofnormal constant elevation and disposed at an elevation lower than thatof the first mentioned weir whereby as the apparatus normally functionssands will be hydraulically passed from the lower portion of the bodyand ultimately will be delivered overthe lower sands overflow Weir.

6. The process of classification comprising feeding a stream of solidsin liquid suspension to a pool having a classifying Azone whose liquidlevel is .fixed during normal operation by a top edge wen` and whoselower limit is a horizontallyextending perforated plate havingassociated anonce? therewith a low Weir normally functioning at constantelevation together with a bale disposed functionally ahead of the lowweir adapted to prevent an outward passage towards the lowl weir ofliquids except such as pass under said baie; continually impartinghorizontal reciprocatory movements to the plate in a manner whereby theplate has repetitive back and forth horizontal movements relative to theoverlying pool and in a manner where there is avoided imparting of anyup or down movement to the plate; continually flowing over the top edgeweir a selected fraction of suspended solids from the zone; maintaininginthe pool at elevation lower than that of the top edge weir andcontiguous to the plate a bed of solids in mobile suspension;continuously effecting passage under the baffle and over the low weir aselected fraction of said suspended solids by supplying to anddistributing throughout the lower portion of 1the zone relativelyconstant upflow currents ofi liquid passing thereto through theperforations in the plate; and controlling the character of solidsselectively passing to the respective fractions principally by thevertical distance between the elevations of the top edge and low overowweirs.

7. Classification apparatus comprising a tank,` a substantiallyhorizontal perforated plate dlvidg ing the tank into an upper and alower compartment, the upper compartment being adapted to serve as aclassification zone for holding a pool of liquid having suspended solidssome of which settle as' a subnatant bed overlying the plate, feed meansVfor the upper compartment, means for supplying liquid under constantpressure through the perforations of the plate; the compartment lowerend therec-f a transfer passageway leading towards the low Weir Vwhilerestricting flow of liquid from the compartment past the low weir, saidweirs and balile being concentrically disposed with respect to theaxisabout which the perforated plate oscillates.

8. Classification apparatus comprising a chamber adapted to hold at xedelevation and against bodily horizontal displaement, a classifying bathof suspended solids having a boundary wall and a bottom that includes aperforated plate, means for supplying a feed of Classifiable solids intothe upperportion of the bath, a suspended fines overflow edge weirextending to the normal liquid level of the-bath and disposedsubstantially marginally of the bath, means providing an upow passagefor sands, a sands overow edge Weir whose upper edge is substantiallylower than that ai the elevation of the edge of the fines Weir, meansfor horizontally oscillating the plate for imparting mobility' to asubmerged bed of settled sands in the lower portion of the bath but atthe same time avoiding imparting vertical bodily movement to the plate,and means for passing water at' relatively constant velocity upwardlythrough the perforations of the plate and through the mobilized bed ofsands under pressure suicient to cause classifying lteeter in the .upperportion of the bath as well as to upiiow classified nes over the nesoverflow weir while permitting settling of classied sands tothemobilized bed of sands, the differential in elevation as between thehigh nes Weir and the lower sands Weir controlling the height of themobilized bed of sands whereby newly classied sands therein cause acorresponding displacement yof sands through said passageway and overthe sands weir.

9. A method of olassication which comprises maintaining at relativelyconstant elevation and against lateral displacement a classifying bathoff suspended solids having a horizontally movable perforated platenormally maintained at constant elevation; distributing a feed ofClassifiable solids applied to the bath substantially at the surfacethereof; balancing the bath containing a bed of settled solids disposedadjacent the plate with an adjustable height of classified sands andwater outside of the bed; continually upilowing water at relativelyconstant but suiiicient pressure through the perforations of the plateand through the bed of sands whereby to effect a classification of thefed solids at the desired cut of sizes in a hydraulically mobilizedportion of the bath above the bed of sands and to overflow classifiedsuspended fines therefrom over and past a Weir edge of re1- ativelyconstant elevation; horizontallyv oscillating the plate relative to thebed to maintain .the

bed of sands in individually mobilized condition;4

and continually discharging from said column beneath a baille and over alow overflow Weir of relatively constant elevation sands in quantityequal to newly classified sands settling to the bed as a result of theclassification action thereupon.

ARTHUR WILLIAM FAHRENWALD.

